Participants in a new study who had more of these markers were at a greater risk of obesity than those with fewer markers — and the more sugar-sweetened beverages that people drank, the wider the gap grew between the groups, in terms of obesity risk.

But little was known about how lifestyle factors, such as the type of food and beverages that people consume, influence weight gain for people with these markers.

The new study suggests people with a genetic predisposition to obesity are more susceptible than others to the harmful effects of sugar-sweetened beverages, the researchers said.

"Our data suggest genetic factors and environmental factors may work together in affecting obesity risk. For those who carry high genetic risk, their risk of obesity could be lessened by [making] healthier beverage choices," said study researcher Lu Qi, assistant professor at Harvard School of Public Health.